Update Cloudflare Workflows integration with comprehensive documentation

Significantly expand the workflows integration documentation with complete
API reference and comprehensive guide based on cloudflare/agents PR #799.

API Reference Updates (run-workflows.mdx):
- Complete AgentWorkflow class documentation with all methods and properties
- Document all 9 Agent workflow methods (runWorkflow, getWorkflow,
  getWorkflows, deleteWorkflow, deleteWorkflows, sendWorkflowEvent,
  approveWorkflow, rejectWorkflow, getWorkflowStatus)
- Add all 5 lifecycle callback methods documentation
- Document workflow tracking table schema and status values
- Add DefaultProgress type definition
- Include manual workflow triggering for advanced use cases

Guide Updates (cloudflare-workflows.mdx):
- Expand from basic example to comprehensive integration guide
- Add complete setup with prerequisites and step-by-step instructions
- Document 5 common patterns: background processing, approval flows,
  retry logic, state sync, custom progress types
- Add bidirectional communication patterns (Agent <-> Workflow)
- Include workflow management (querying and cleanup)
- Add best practices for design, state, failures, and monitoring
- Document limitations clearly
- Add cross-references to related documentation

Key features documented:
- Automatic workflow tracking in SQLite
- Typed progress reporting with custom types
- Human-in-the-loop approval helpers (waitForApproval, approve/reject)
- State synchronization (updateAgentState, mergeAgentState)
- WebSocket broadcasting from workflows
- Workflow querying with metadata filters
- Retention policies and cleanup strategies

All content follows Cloudflare docs style: TypeScriptExample components,
WranglerConfig component, proper link formatting, no contractions.

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: github-actions[bot]